Hybrid silicon-metal anode using microparticles for lithium-ion batteries

ABSTRACT

A system and method of forming a silicon-hybrid anode material. The silicon-hybrid anode material including a microparticle mixture of a quantity of silicon microparticles and a quantity of metal microparticles intermixed with the quantity of silicon microparticles in a selected ratio. The microparticle mixture is formed in a silicon-hybrid anode material layer having a thickness of between about 2 and about 15 μm.

BACKGROUND

The present invention relates generally to electrical power storagesystems, and more particularly, to methods and systems for makinglithium-ion batteries.

Traditional lithium ion batteries lack sufficient energy density(Watt-hours/kilogram) for many electrical systems. By way of example,the insufficient energy density of traditional lithium-ion batterieslimits the electric vehicle driving range between recharges. Electricvehicles are a major step in moving transportation systems of a modem,energy based economy away from greenhouse gas emitting fossil fuelengines.

In view of the foregoing, there is a need for an electrical energystorage solution with a greater energy density than traditionallithium-ion batteries.

SUMMARY

Broadly speaking, the present invention fills these needs by providing alithium-ion battery using microparticles as an electrical energy storagesolution electrical power storage system. It should be appreciated thatthe present invention can be implemented in numerous ways, including asa process, an apparatus, a system, computer readable media, or a device.Several inventive embodiments of the present invention are describedbelow.

One embodiment provides a system and method of forming a silicon-hybridanode material. The silicon-hybrid anode material including amicroparticle mixture of a quantity of silicon microparticles and aquantity of metal microparticles intermixed with the quantity of siliconmicroparticles in a selected ratio. The microparticle mixture is formedin a silicon-hybrid anode material layer having a thickness of betweenabout 2 and about 15 μm.

The microparticle mixture can include a quantity of at least one bindermaterial. The microparticle mixture can be heated and the quantity of atleast one binder material is substantially evaporated away. Themicroparticle mixture can be annealed.

The quantity of silicon microparticles can have a size range of betweenabout 1 micrometer and about 20 micrometers. The quantity of metalmicroparticles has a size range of between about 1 micrometer and about30 micrometers. The size of the silicon microparticles can besubstantially equal to the size of the metal microparticles.

The selected ratio of the microparticle mixture includes between about10 percent and about 40 percent, by weight, of silicon microparticlesand between about 90 percent and about 60 percent, by weight, of metalmicroparticles. The binder is between about 5 percent and about 10percent by weight of the microparticle mixture.

At least one silicon-hybrid anode material layer can be included in abattery. The battery can be a lithium-ion battery. The lithium-ionbattery can also include a lithium containing electrolyte, a quantity ofseparator material is included within the lithium containing electrolyteand a cathode disposed on a side of the electrolyte opposite from the atleast one silicon-hybrid anode material layer.

Another embodiment provides a method of forming a silicon-hybrid anodematerial. The method includes forming a quantity of siliconmicroparticles, forming a quantity of metal microparticles, mixing thequantity of silicon microparticles and the quantity of metalmicroparticles in a selected ratio to form a microparticle mixture andforming the microparticle mixture into a silicon-hybrid anode materiallayer having a thickness of between about 2 and about 15 μm.

Other aspects and advantages of the invention will become apparent fromthe following detailed description, taken in conjunction with theaccompanying drawings, illustrating by way of example the principles ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be readily understood by the followingdetailed description in conjunction with the accompanying drawings.

FIG. 1 is a simplified schematic of a lithium-ion battery including ahybrid, silicon-based microparticle anode material, in accordance withembodiments of the present invention.

FIG. 2 is a simplified schematic of a microwave induced decompositionreactor chamber system, in accordance with embodiments of the presentinvention.

FIG. 3 is a flowchart diagram that illustrates the method operationsperformed in forming the silicon microparticles, in accordance withembodiments of the present invention.

FIG. 4 is a flowchart diagram that illustrates the method operationsperformed in forming soft metal microparticles, in accordance withembodiments of the present invention.

FIG. 5 is a flowchart diagram that illustrates an alternative methodoperations performed in forming soft metal microparticles by thermalevaporation, in accordance with embodiments of the present invention.

FIG. 6 is a flowchart diagram that illustrates the method operationsperformed in forming a lithium-ion battery including the hybridsilicon-based anode material, in accordance with embodiments of thepresent invention.

FIG. 7 is a simplified schematic of a mixing system, in accordance withembodiments of the present invention.

FIG. 8 is a simplified schematic of an annealing chamber system, inaccordance with embodiments of the present invention.

FIG. 9 is a graphical representation of the lithium-ion relationship, inaccordance with embodiments of the present invention.

FIG. 10 is a cross-sectional view of a rolled layer lithium ion battery,in accordance with embodiments of the present invention.

FIG. 11 is a block diagram of an exemplary computer system for carryingout the processing according to the invention.

FIG. 12 is a block diagram of an integrated system including one or moreof the microwave decomposition reactor systems, mixing system andannealing system, in accordance with an embodiment of the presentinvention.

DETAILED DESCRIPTION

Several exemplary embodiments for a lithium-ion battery usingmicroparticles as an electrical energy storage solution, electricalpower storage system and methods will now be described. It will beapparent to those skilled in the art that the present invention may bepracticed without some or all of the specific details set forth herein.

Typically available lithium-ion battery packs, such as may be used in anelectric vehicle (EV), are prohibitively expensive for powering a masstransportation system.

Conventional lithium-ion batteries use carbon-based graphite anodes.Silicon (Si) is a promising anode materials in solid state lithium-ionbattery applications due to the high charge density and low operationvoltage with maximum lithium uptake of Li/Si=4.4/1.0, Li₂₂Si₅. By way ofexample, a higher charge density for silicon is 3,579 milli-amp-hoursper gram (mAh g⁻¹) at ambient temperature as compared to the maximumtheoretical charge density of 372 mAh g⁻¹ for a conventional graphiteanode system.

Unfortunately the volume of a bulk silicon anode drastically expandsduring the lithium-ion intercalation (i.e., lithiation). At the reducedvolume of materials, surface-to-volume ratio increased and “bulkproperties” of the materials can be affected substantially.

In contrast, silicon nanoparticles demonstrate different chemical andphysical properties from the bulk silicon properties allowed by thesignificant smaller physical size (e.g., between about 10⁻⁹ and about10⁻⁶ meter) for each nanoparticle as compared to the bulk silicon.Unfortunately, silicon nanoparticles as an anode electrode in alithium-ion battery system demonstrated approximately 400% volumeexpansion/contraction of the silicon during the charge/lithiation anddischarge/delithiation phases. This drastic silicon volume change duringthe charge/lithiation and discharge/delithiation cycles causes a majordegradation of the silicon anode lithium-ion battery and leads to aneventual electrode failure.

A new hybrid silicon-based anode material for a lithium-ion battery isdisclosed below. The disclosed hybrid silicon-based anode materials canbe binary or ternary or more element hybrid silicon-soft metalmicroparticles. Suitable soft metals include metals that arepolarizable. Neutral nonpolar species have spherically symmetricarrangements of electrons in their electron clouds. When in the presenceof an electric field, neutral nonpolar species electron clouds can bedistorted. The ease of this distortion is defined as the polarizabilityof the atom or molecule. Polarizable means species has an easilydistorted cloud of electrons. In general, polarizability of an atomcorrelates with the interaction between electrons and the nucleus. Theamount of electrons in a molecule affects how closely or tightly thenuclear charge can control the overall charge distribution. Atoms withfewer electrons have smaller, denser electron clouds, as there is astrong interaction between the few electron's orbitals and thepositively charged nucleus. There is also less shielding in atoms withless electrons contributing to the stronger interaction of the outerelectrons and the nucleus.

By way of example, in a two atom molecule, the electrons may beattracted to the nuclei of both atoms. However, if a first nucleusattracts more strongly than the other (usually because the first atomhas fewer electrons held in a denser cloud), then the bonding electronsfrom both nuclei tend to be located closer to the first nucleus than theother nucleus. As a result, the bonding electrons are unevenlydistributed and form a polar bond between the two atoms, in contrast,when electrons experience an equal attractive force to both nuclei, thebond is non-polar. Polarizability also affects dispersion forces throughthe molecular shape of the affected molecules. Elongated molecules haveelectrons that are easily moved increasing, their polarizability andthus strengthening the dispersion forces. In contrast, small, compact,symmetrical molecules are less polarizable resulting in weakerdispersion forces. Dispersion forces are a type of force acting betweenatoms and molecules. Therefore, the polarization is caused by bothintramolecular force (all type of chemical bond) and intermolecularforce (induced instantaneous polarization multi-poles in molecules).

Some example suitable soft metals include tin (Sn), copper (Cu),platinum (Pt), gold (Au), thallium (Tl), lead (Pb), mercury (Hg),cadmium (Cd), silver (Ag), aluminum (Al) and germanium (Ge) andcombinations thereof and other suitable soft metals can be useful forfabrication of hybrid silicon anode materials. The soft metal used isideally at least 99.9% pure, however it should be understood that agreater purity (e.g., about 99.99% or more) soft metal and somewhat lesspurity (e.g., about 99% purity or less) soft metal can be used.

The hybrid silicon-based anode materials can use binary microparticlessuch as silicon and one soft metal, by way of example Si—Sn. The hybridsilicon-based anode materials can use ternary microparticles such assilicon and two soft metals, by way of example Si—Sn—C, or othercombinations of silicon and soft metal microparticles. More complexexamples having four or more materials include Si—Sn—Ag (silver)-C orSi—Sn—Ag—Al (aluminum)-C. The hybrid silicon-based anode materialsreduce silicon volume changes significantly without losing capacityduring the lithiation/charge and delithiation/discharge phases.

As will be described in more detail below, the hybrid silicon-basedanode material is also annealed. The annealed, hybrid structure ofhybrid silicon-based anode material particles relieves the stressoccurring during the expansion and contraction of the silicon during therespective lithiation/charge and delithiation/discharge phases. Theannealing processing of the hybrid silicon-based anode material particlegeometries substantially prevents cracking, buckling and eventualaggregation of the silicon-based anodes, thus improving the capacity andcycle life. The hybrid silicon-based anode material can have a chargedensity of greater than about 3,500 mAh g⁻¹.

The hybrid silicon-based anode materials are compatible with othertypical lithium-ion battery materials and thus require no otherlithium-ion battery structural or material changes. Therefore, knowncathode materials such as lithium cobalt oxide (LiCoO₂), lithiummanganese oxide (LiMn₂O₄), lithium vanadium oxide (LiV₂O₅), lithium ironphosphate (LiFePO₄), lithium nickel manganese cobalt oxide(Li_(x)Ni_(y)Co_(z)Mg_(m)O₂), and lithium nickel cobalt aluminum oxide(Li_(x)Ni_(y)Co_(z)Al_(m)O₂) and solid electrolytes used in conventionallithium-ion battery structures can be used with the hybrid silicon-basedanode materials as shown in FIG. 1. The lithium-ion battery structuredescribed herein include carbonate-based electrolytes and/or polymerelectrolyte and/or solid inorganic electrolytes having a lithium-ionconductivity of greater than about 5×10⁻³ S/cm and are matched with thehybrid silicon-based anode material.

Optionally, a separator material of either polyethylene or polypropylenecan be included in the battery. The separator materials are locatedanywhere between the anode and cathode such as being mixed within theelectrolyte. The separator material acts as a thermal “fuse” and meltswhen the lithium-ion battery overheats to greater than about 120 toabout 170 degrees C. as may be chosen for the desired application. Themelted separator material stops the lithium-ion flow between anode andcathode, thus preventing an uncontrolled exothermic event such as mayoccur in an accidental short circuit of the battery anode to the cathodeor other excessive power draw from or excessive power input to thehybrid silicon-based anode, lithium-ion battery.

FIG. 1 is a simplified schematic of a lithium-ion battery 100 includinga hybrid, silicon-based microparticle anode material, in accordance withembodiments of the present invention. The lithium-ion battery 100includes a cathode current conductor 102 and an anode current conductor110. The cathode current conductor 102 and the anode current conductor110 are typically formed of copper, copper alloy or other highlyconductive metal. A lithium containing cathode 104 is in electricalcontact with the cathode current conductor 102. A hybrid silicon-basedmicroparticle anode material 108 is in electrical contact with the anodecurrent conductor 110. The hybrid silicon-based microparticle anodematerial is described in more detail below. A solid electrolyte 106 isdisposed between the lithium containing cathode 104 and the siliconhybrid anode 108.

Microwave chemistry relies on the ability of the reaction mixture toabsorb microwave energy coupled into the gas flow forming plasma such asdipolar polarization or ionic conduction mechanisms. This produces rapidthermal internal heating by direct interaction between electromagneticirradiation and reagent molecules. Applying a sufficiently highmicrowave field density can cause decomposition of source gas flows. Thedecomposition products can then be used to form hybrid silicone-metalmaterials and/or hybrid silicon-carbonaceous materials.

A high speed microwave synthetic method was used to produce siliconmicroparticles. The microwave induced electrical discharge dissociationof silane (SiH₄) or disilane (Si₂H₆) with a mixture of hydrogen (H₂) andargon (Ar) gas produces Si microparticles in a low pressure flowreactor.

FIG. 2 is a simplified schematic of a microwave induced decompositionreactor chamber system 200, in accordance with embodiments of thepresent invention. The microwave induced decomposition reactor chambersystem 200 includes a microwave induced decomposition reactor chamber202 and a microwave generator 204 for generating a microwave fieldwithin the microwave induced decomposition reactor chamber 202. Themicrowave induced decomposition reactor chamber system 200 also includesmultiple process gas sources 210A, 210B, 210C coupled through respectiveflow control devices 212A, 212B, 212C to a nozzle 208 disposed insidethe microwave induced decomposition reactor chamber 202.

The microwave induced decomposition reactor chamber system 200 alsoincludes a cooling chamber 206. The cooling chamber 206 includes cooledwalls 214 as will be described in more detail below. A cooling system216 is coupled to the cooled walls 214 to maintain the cooled walls at adesired temperature. The cooling chamber 206 also includes an outletchamber 218 located downstream of the cooled walls 214. A pump 222 drawsthe flow of the process gases in a direction 222A from the nozzle 208and into the outlet chamber 218. An outlet port 220 couples the outletchamber 218 to a collector 224. The collector 224 can optionally includea temperature control system 226 to maintain the collector at a desiredcollector temperature.

The microwave induced decomposition reactor chamber system 200 alsoincludes a controller 230 for controlling the processes in each portionof the microwave induced decomposition reactor chamber system. Thecontroller 230 is coupled to the process gas sources 210A, 210B, 210C,the microwave induced decomposition reactor chamber 202, the coolingchamber 206 and the temperature control system 226. The controller 230includes software 232, logic 234 and processing capability to control,monitor and operate the various components in the microwave induceddecomposition reactor chamber system 200.

FIG. 3 is a flowchart diagram that illustrates the method operations 300performed in forming the silicon microparticles, in accordance withembodiments of the present invention. The operations illustrated hereinare by way of example, as it should be understood that some operationsmay have sub-operations and in other instances, certain operationsdescribed herein may not be included in the illustrated operations. Withthis in mind, the method and operations 300 will now be described.

In an operation 305, a process gas mixture of a silicon source material(e.g., silane (SiH₄) or other suitable silicon source material),hydrogen (H₂) and argon (Ar) is injected into the microwave generatorchamber 202 through a nozzle 208. The silicon source material (Silane,Disilane), hydrogen and argon gases can be mixed in a mixer 209 beforeinjection into the nozzle 208. The ratio of the reduction or burning gas(H₂), depending on the morphology of the synthesized silicon particles,and the carrier gas (Ar) can be varied, between about 1 part (H₂) to 50parts (Ar) (1:50 ratio) and 2 part (H₂) to 50 parts (Ar) (2:50 ratio).Flowrate of the gas mixture is between about 10-20 slpm (standard litersper minute) in to the microwave generator chamber. The silane (SiH₄) ofat least 99% purity and hydrogen (H₂) and argon (Ar) are each about99.99% pure (e.g. “four nines purity”). It should be understood thateven greater purity gases could also be used. The respective flow ratesof the silane (SiH₄), hydrogen (H₂) and argon (Ar) are monitored bycalibrated flow meters and controlled to determine the siliconmicroparticle size distribution.

In an operation 310, about 900 W radio frequency power, at about 2.45GHz frequency, is applied to the microwave generator chamber to form aplasma in the microwave generator chamber due to the excitation causedby the applied RF power. The microwave generator chamber can be operatedat a reaction temperature of between about 300 degrees C. and about 700degrees C. and at a pressure of between about 100 mTorr and about 100Torr.

In an operation 315, the plasma produced by Ar in the radio-frequencyelectric current dissociates the silane (SiH₄) with hydrogen (H₂) toproduce silicon ions 209A. The disassociated silicon ions 209A are drawnout of the microwave generator chamber in direction 222A and past one ormore a cold walls 214 to cool the disassociated silicon ions 209A, in anoperation 320.

The reduced silicon species can be cooled and aggregated to form siliconmicroparticles 209A′ in an operation 325. The extra hydrogen 209B cooland are drawn into the pump 222. The cold walls 214, 220 have atemperature range of between about 25 degrees C. and about minus 196degrees C., so as to sufficiently cool the disassociated silicon ions209A and hydrogen 209B. The cold walls 214 can be cooled by any suitablecoolant such as liquid nitrogen, water, ethylene glycol, dry ice (i.e.,solid form carbon dioxide) in acetone, or any other suitable coolingsystem or media. The formed silicon microparticles 209A′ pass throughcold walls 220 and the particle size range in the collector 224 isbetween about 1 to about 20 μm after passing near the cold walls 220.The formed silicon microparticle 209A′ size distribution can be selectedby power of the microwave generator, flow rate of the process gasreactants and ratio of the reactants. As power of the microwave isincreased, the formed plasma is able to reduce the reaction energy atlow reaction temperatures (e.g., about ambient temperatures of betweenabout 20 and about 35 degrees C.). The size distribution of the formedparticles can be affected by the reactant concentration and flow rate.In general, the agglomeration during the transport is a result of thehigh concentration (mass, molar, number and volume concentration) of thereactants. Another important factor for the particle size distributionis the cooling temperature of the cold wall.

The concentration of silane in the above mentioned gas mixture usinghydrogen and argon (1-2% of hydrogen) is varied in the range of 1,000ppm to 10,000 ppm. The microwave generator 204 can operate up to about2,000 W output power at 2.45 GHz frequency and can be operated at areaction temperature from 25 to 700° C. and under from 100 m Torr to 100Torr. The morphology of the generated silicon particles depends onreaction temperature. For example, small crystals surrounded byamorphous particles can be synthesized under 300° C., howevercrystalline structure of particles can be collected above 600° C.

In an operation 330, the formed silicon microparticles 209A″ arecollected in a collector 224. The collector 224 can include multiplelayers of nets. The nets are formed of a suitable sieve material such assteel, stainless steel, copper, nickel and alloys thereof and any othersuitable material. The nets have openings of between about 15 to about20 micrometer width. In an optional operation 335, the collected siliconmicroparticles 209A″ are milled to a desired microparticle size and themethod operations can end. After synthesis of the silicon microparticles209A″ can be milled process using a milling machine such as conventionalvibrating ball milling machine to achieve narrow particle sizedistribution (1-5 micrometer).

The soft metal microparticles can be formed substantially similarly tothe silicon microparticles as described in FIG. 3 above. FIG. 4 is aflowchart diagram that illustrates the method operations 400 performedin forming soft metal microparticles, in accordance with embodiments ofthe present invention. The operations illustrated herein are by way ofexample, as it should be understood that some operations may havesub-operations and in other instances, certain operations describedherein may not be included in the illustrated operations. With this inmind, the method and operations 400 will now be described. By way ofexample, tin (Sn) microparticles can also synthesized using a gasmixture of soft metal source material such as tetramethyltin (Sn(CH₃)₄,TMT) as a tin source material, hydrogen (H₂) and argon (Ar).

In an operation 405, a gas mixture of TMT, hydrogen (H₂) and argon (Ar)is injected into the microwave generator chamber. Flowrate of the gasmixture is between about 10 and about 20 standard liters per minute(slpm) into the microwave generator chamber. The concentration of theTMT is between about 2000 and about 8000 ppm in the mixture. The TMT isabout 99% pure and the hydrogen (H₂) and argon (Ar) are each about99.99% pure (e.g. “four nines purity”). It should be understood thateven greater purity gases could also be used. The respective flow ratesof the tetramethyltin (Sn(CH₃)₄, TMT), H₂ and Ar are monitored bycalibrated flow meters and controlled to determine the tin microparticlesize distribution and synthesis. The decomposition of tin sourcematerial in the reactor, the reaction temperature and the residence timeof the tin species in the reactor are important parameters of the tinparticle synthesis and size distribution. Alternatives to tin sourcematerials than TMT include, but are not limited to Tetramethyltin,Tetravinyltin (Sn(CH═CH₂)₄), Trimethyl(phenyl)tin (C₆H5Sn(CH₃)₃),Tricyclohexyltin hydride ((C₆H₁₁)SnH) and Hexaphenylditin ((C₆H₅)₃Sn)₂).

In an operation 410, about 900 W radio frequency power, at about 2.45GHz frequency, is applied to the microwave generator chamber to form aplasma in the microwave generator chamber due to the excitation causedby the applied RF power. The microwave generator chamber can be operatedat a reaction temperature of between about 25 and about 700 degrees C.and at a pressure of between about 100 mTorr and about 100 Torr.Amorphous tin microparticles particles can be formed at an ambienttemperature of about 25 degrees C., however, polycrystalline tinmicroparticles can be formed above 300 degrees C. A combination ofamorphous tin microparticles and polycrystalline tin microparticles canbe used in various ratio combinations to form the hybrid silicon anodematerials.

In an operation 415, the plasma dissociates the TMT to produce tin andhydrogen. The disassociated tin and hydrogen are drawn out of themicrowave generator chamber and past one or more cold walls to cool thedisassociated tin and hydrogen, in an operation 420. The formed tinspecies 209A can form tin microparticles as the tin passes through thecold wall 220. The formed particle size distribution can be controlledby the cooling temperature from about 25 degrees C. to about −196degrees C. The cold wall 220 has the lowest temperature in the particlesynthetic process.

In an operation 425, the formed tin microparticles are collected in atemperature controlled collector 224. The collector 224 can includemultiple layers of nets. The nets are formed of a suitable sievematerial such as steel, stainless steel, copper, nickel and alloysthereof and any other suitable material. The nets have openings ofbetween about 15 to about 20 micrometer width. The particle collector224 is maintained at approximately ambient temperature of between about15 degrees C. and about 30 degrees C. In an optional operation 430, thecollected tin microparticles are milled to a desired microparticle sizeand the method operations can end.

FIG. 5 is a flowchart diagram that illustrates an alternative methodoperations 500 performed in forming soft metal microparticles by thermalevaporation, in accordance with embodiments of the present invention.The operations illustrated herein are by way of example, as it should beunderstood that some operations may have sub-operations and in otherinstances, certain operations described herein may not be included inthe illustrated operations. With this in mind, the method and operations500 will now be described. By way of example, tin (Sn) microparticlescan also synthesized using a gas mixture of tetramethyltin (Sn(CH₃)₄,TMT), hydrogen (H₂) and argon (Ar) in a thermal evaporation process.

In an operation 505, a gas mixture of TMT, hydrogen (H₂) and argon (Ar)is injected into a processing chamber. Flowrate of the gas mixture isbetween about 10-20 slpm (standard liters per minute) into theprocessing chamber.

In an operation 510 the gas mixture is heated by a heat source tobetween about 25 to about 300 degrees C. The heat source can be anysuitable heat source such as resistive heater, an electron beam heater(such as may be found in a typical sputtering reactor). For resistiveheat source, the heater elements draw electrical current as high as50-100 A or more and voltage as low as 6-20V.

In an operation 515, the heated gas mixture dissociates the TMT toproduce tin and hydrogen. The disassociated tin and hydrogen are drawnout of the processing chamber and past one or more cold walls to coolthe disassociated tin and hydrogen ions, in an operation 520. The tinmicroparticles form in a size range of between about 1 and about 30 μm.

In an operation 525, the formed tin microparticles are collected in atemperature controlled collector. In an optional operation 530, thecollected tin microparticles are milled to a desired microparticle sizeand the method operations can end.

Composite materials are prepared by thermal or mechanical process. Forexample, pyrolysis, mechanical mixing and milling, or some combinationsof thermal and mechanical methods are useful preparation techniques. Thehybrid binary silicon-based anode materials can include of silicon andtin microparticles on solid substrates. The hybrid ternary silicon-basedanode materials can include silicon and tin microparticles withcarbonaceous microparticles as a third ingredient.

FIG. 6 is a flowchart diagram that illustrates the method operations 600performed in forming a lithium-ion battery including the hybridsilicon-based anode material, in accordance with embodiments of thepresent invention. The operations illustrated herein are by way ofexample, as it should be understood that some operations may havesub-operations and in other instances, certain operations describedherein may not be included in the illustrated operations. With this inmind, the method and operations 600 will now be described. The hybridbinary silicon-based anode materials for a lithium-ion battery arecomposed of silicon and tin microparticles formed as described above inFIGS. 3-5.

FIG. 7 is a simplified schematic of a mixing system 700, in accordancewith embodiments of the present invention. The mixing system 700includes a mixture receptacle 702 and a mixer 704.

In an operation 605, a quantity of the silicon microparticles 710A and aquantity of the tin microparticles 710B are combined in a selected ratiowith a quantity of one or more binder materials 710C in the mixturereceptacle 702 to form a microparticle mixture. The microparticles forthe hybrid anode materials include the polymer binder of about 5-10percent by weight of the anode materials. The ratio ranges of thesilicon microparticles and tin microparticles are shown in FIG. 9. Byway of example the microparticle mixture can include between about 10percent and about 40 percent, by weight, of silicon microparticles andbetween about 90 percent and about 60 percent, by weight, of metalmicroparticles.

Suitable binders can include poly vinylidene fluoride (PVDF), carbonmaterial (carbon black, graphite powder, and carbon fiber, etc.),styrene butadiene rubber (SBR), including gel electrolyte such aspolyethylene oxide (PEO), polyacrylonitrile (PAN), poly vinylidenefluoride (PVDF) and poly methyl methacrylate (PMMA).

In an operation 610, combination of the quantity of the siliconmicroparticles, the quantity of the tin microparticles and the quantityof one or more binder materials are mixed by the mixer 704 to form amixture 710. The mixer 700 can be a ball type grinding mill and mixerfor mixing and milling the mixture in a single operation. A ball typegrinding mill and mixer can form microparticles as small as about 5micrometer.

FIG. 8 is a simplified schematic of an annealing chamber system 800, inaccordance with embodiments of the present invention. The annealingchamber system 800 includes an annealing chamber 802 and at least onegas source 804. The annealing chamber 802 includes a heat source 806 forheating the contents of the annealing chamber. The annealing chamber 802also includes a controller 810 for controlling the annealing chambersystem 800.

In an operation 615, the mixture 710 is moved to the annealing chamber802. The annealing chamber has an inert gas environment (e.g., argon ornitrogen). The inert gas flow rate into the annealing chamber is betweenabout 50 and about 300 standard cubic centimeters per minute (SCCM).

In an operation 620, the mixed silicon microparticles, tinmicroparticles and binder materials are heated at a temperature gradientof between 200 and 650 degrees C. over a period of time of between about5 hours and about 24 hours. Heating the mixed silicon microparticles,tin microparticles and binder materials binds the silicon microparticlesand tin microparticles together and the binder materials aresubstantially evaporated away.

In an operation 625, the bound silicon microparticles and tinmicroparticles are gradually cooled to a cooled temperature of betweenabout 45 and about 60 degrees C. over a period of time between about 1hour and about 10 hours to produce an annealed quantity of siliconmicroparticles and tin microparticles.

In an operation 630, the annealed silicon microparticles, tinmicroparticles are pressed into a layer having a thickness of betweenabout 2 and about 15 μm. Pressing the annealed silicon microparticles,tin microparticles can be achieved using a conventional press havingbetween about 3.0 kg/cm² and about 15.0 kg/cm² to produce a layer ofhybrid silicon-based anode material.

In an operation 635, one or more layers of hybrid silicon-based anodematerial are combined with electrolyte and cathode layers to form thelithium-ion battery of the desired form factor.

FIG. 9 is a graphical representation 900 of the lithium-ionrelationship, in accordance with embodiments of the present invention.For a specific lithium-ion capacity, the anode materials are designedand fabricated using appropriate ratio between silicon and soft metal(e.g., tin). The ratio of silicon and soft metal is an important factorfor the electrochemical performance. By way of example, for the Si—Snanode materials in the lithium-ion battery system. The composition ratioin the each hybrid system is optimized for the best electrochemicalperformance during the battery charge/litiation anddischarge/delithiation cycles. In the binary hybrid microparticlestructure, the atomic ratio of Si:Sn can be varied from about 1:9 toabout 4:6

For the ternary hybrid silicon-based microparticle anode materials,silicon, tin and carbon are main ingredients of the Si-based anodematerials. Carbon as a third material for the ternary hybrid structure,the ratio of ternary particles (Si:Sn:C) is 30% of Si, 30% of Sn and 40%of carbon, respectively.

Compared to conventional lithium-ion batteries using graphite anodes orsilicone-graphene anodes, the hybrid silicon-based microparticle anodematerials described herein can minimize silicon volume changes due tolithium insertion and extraction. The microparticles size of 0.5-5 μmresult in minimal diffusion path length through the Si-based anodes.This approach improves packing density to maximize lithium-ions duringthe lithiation and offers improved stability and enhanced capacity withinexpensive methods such as may be useful in an electric vehicle.

The voltage, energy capacity, power, life, and safety of the lithium-ionbattery using hybrid silicon-based microparticle anode for an electricvehicle can be changed due to the respective chemical and physicalproperties by materials selection because the composition in the anodesis tunable and can be controlled during the fabrication.

FIG. 10 is a cross-sectional view of a rolled layer lithium ion battery1000, in accordance with embodiments of the present invention. Thelithium ion battery 1000 is substantially cylindrical in form. Thelithium ion battery 1000 includes one or more cathode layers 1002, 1004with a cathode current collector 1003 between each pair of cathodelayers. The lithium ion battery 1000 also includes one or more anodelayers 1006, 1008 with an anode current collector 1007 between each pairof anode layers. A separator layer is disposed between the cathode layer1004 and the anode layer 1006 so as to separate the anode from thecathode. A quantity of electrolyte 1010 is in contact with at least oneend of the rolled layers 1001-1009. The outer layers 1001, 1009 can beseparator material or other suitable non-conductive materials.

Alternatively, the layer lithium ion battery can be formed in a stack ofhybrid silicon-based microparticle anode layers and cathode layers. In astacked configuration, the three layers are enclosed in separator layersand the respective edges can be sealed. A gel electrolyte can be used toprevent electrolyte from leaking.

As described above the lithium-ion battery includes a hybrid silicon andsoft metal binary or ternerary microparticle anodes for a safe electricvehicle battery. The lithium-ion battery includes shutdown functionseparators to be protected by potential electrochemical and thermalreaction such as overcharge or short-circuiting.

FIG. 11 is a block diagram of an exemplary computer system 1100 forcarrying out the processing according to the invention. The computersystem 1100 can be coupled to one or more of the microwave decompositionreactor systems 200, mixing system 700 and annealing system 800 tocontrol the operations of thereof (e.g., controller 230, 810, etc.). Thecomputer system 1100 includes a digital computer 1102, a display screen(or monitor) 1104, a printer 1106, a floppy disk or other computerreadable media that is removable 1108, a hard disk drive or similarpersistent storage device 1110, a network interface 1112, and a keyboard1114. The digital computer 1102 includes a microprocessor 1116, a memorybus 1118, random access memory (RAM) 1120, read only memory (ROM) 1122,a peripheral bus 1124, and a keyboard controller (KBC) 1126. The digitalcomputer 1102 can be a personal computer (such as an IBM compatiblepersonal computer, a Macintosh computer or Macintosh compatiblecomputer), a workstation computer (such as a Sun Microsystems orHewlett-Packard workstation), or some other type of computer.

The microprocessor 1116 is a general purpose digital processor, whichcontrols the operation of the computer system 1100. The microprocessor1116 can be a single-chip processor or can be implemented with multiplecomponents. Using instructions retrieved from memory, the microprocessor1116 controls the reception and manipulation of input data and theoutput and display of data on output devices.

The memory bus 1118 is used by the microprocessor 1116 to access the RAM1120 and the ROM 1122. The RAM 1120 is used by the microprocessor 1116as a general storage area and as scratch-pad memory, and can also beused to store input data and processed data. The ROM 1122 can be used tostore instructions or program code followed by the microprocessor 1116as well as other data.

The peripheral bus 1124 is used to access the input, output, and storagedevices used by the digital computer 1102. In the described embodiment,these devices include the display screen 1104, the printer device 1106,the floppy disk drive 1108, the hard disk drive 1110, and the networkinterface 1112. The keyboard controller 1126 is used to receive inputfrom keyboard 1114 and send decoded symbols for each pressed key tomicroprocessor 1116 over bus 1128.

The display screen 1104 is an output device that displays images of dataprovided by the microprocessor 1116 via the peripheral bus 1124 orprovided by other components in the computer system 1100. The printerdevice 1106, when operating as a printer, provides an image on a sheetof paper or a similar surface. Other output devices such as a plotter,typesetter, etc. can be used in place of, or in addition to, the printerdevice 1106.

The floppy disk or other removable computer readable media 1108 and thehard disk drive or other persistent storage media 1110 can be used tostore various types of data. The floppy disk drive 1108 facilitatestransporting such data to other computer systems, and hard disk drive1110 permits fast access to large amounts of stored data.

The microprocessor 1116 together with an operating system operate toexecute computer code and produce and use data. The computer code anddata may reside on the RAM 1120, the ROM 1122, or the hard disk drive1110. The computer code and data could also reside on a removableprogram medium and loaded or installed onto the computer system 1100when needed. Removable program media include, for example, CD-ROM,PC-CARD, floppy disk, flash memory, optical media and magnetic tape.

The network interface 1112 is used to send and receive data over anetwork connected to other computer systems. An interface card orsimilar device and appropriate software implemented by themicroprocessor 1116 can be used to connect the computer system 1100 toan existing network and transfer data according to standard protocols.

The keyboard 1114 is used by a user to input commands and otherinstructions to the computer system 1100. Other types of user inputdevices can also be used in conjunction with the present invention. Forexample, pointing devices such as a computer mouse, a track ball, astylus, or a tablet can be used to manipulate a pointer on a screen of ageneral-purpose computer.

FIG. 12 is a block diagram of an integrated system 1200 including one ormore of the microwave decomposition reactor systems 200, mixing system700 and annealing system 800, in accordance with an embodiment of thepresent invention. The integrated system 1200 includes the one or moreof the microwave decomposition reactor systems 200, mixing system 700and annealing system 800 and an integrated system controller 1210coupled to the systems 200, 700, 800. Additional systems, not shown, canalso be included and coupled to and controlled by the integrated systemcontroller 1210. The integrated system controller 1210 includes or iscoupled to (e.g., via a wired or wireless network 1212) a user interface1214. The user interface 1214 provides user readable outputs andindications and can receive user inputs and provides user access to theintegrated system controller 1210.

The integrated system controller 1210 can include a special purposecomputer or a general purpose computer. The integrated system controller1210 can execute computer programs and/or logic 1216 to monitor, controland collect and store data 1218 (e.g., performance history, analysis ofperformance or defects, operator logs, and history, etc.) for thedeposition systems 300, 400 and production system 350. By way ofexample, the integrated system controller 1210 can adjust the operationsof the deposition systems 300, 400 and production system 350 and/or thecomponents therein (e.g., the temperatures, flow rates, pressures,locations, movement, loading and unloading of the substrate 102, etc.)if data collected dictates an adjustment to the operation thereof.

It should be understood that while the soft metal of tin was selectedfor the above embodiments, any suitable soft metal can be used insimilar processes to form the hybrid silicon-based anode materials.

With the above embodiments in mind, it should be understood that theinvention may employ various computer-implemented operations involvingdata stored in computer systems. These operations are those requiringphysical manipulation of physical quantities. Usually, though notnecessarily, these quantities take the form of electrical or magneticsignals capable of being stored, transferred, combined, compared, andotherwise manipulated. Further, the manipulations performed are oftenreferred to in terms, such as producing, identifying, determining, orcomparing.

Any of the operations described herein that form part of the inventionare useful machine operations. The invention also relates to a device oran apparatus for performing these operations. The apparatus may bespecially constructed for the required purposes, or it may be ageneral-purpose computer selectively activated or configured by acomputer program stored in the computer. In particular, variousgeneral-purpose machines may be used with computer programs written inaccordance with the teachings herein, or it may be more convenient toconstruct a more specialized apparatus to perform the requiredoperations.

The invention can also be embodied as computer readable code and/orlogic on a computer readable medium. The computer readable medium is anydata storage device that can store data which can thereafter be read bya computer system. Examples of the computer readable medium include harddrives, network attached storage (NAS), logic circuits, read-onlymemory, random-access memory, CD-ROMs, CD-Rs, CD-RWs, magnetic tapes,and other optical and non-optical data storage devices. The computerreadable medium can also be distributed over a network coupled computersystems so that the computer readable code is stored and executed in adistributed fashion.

It will be further appreciated that the instructions represented by theoperations in the above figures are not required to be performed in theorder illustrated, and that all the processing represented by theoperations may not be necessary to practice the invention. Further, theprocesses described in any of the above figures can also be implementedin software stored in any one of or combinations of the RAM, the ROM, orthe hard disk drive.

Although the foregoing invention has been described in some detail forpurposes of clarity of understanding, it will be apparent that certainchanges and modifications may be practiced within the scope of theappended claims. Accordingly, the present embodiments are to beconsidered as illustrative and not restrictive, and the invention is notto be limited to the details given herein, but may be modified withinthe scope and equivalents of the appended claims.

What is claimed is:
 1. A silicon-hybrid anode material comprising: amicroparticle mixture including: a quantity of silicon microparticles;and a quantity of metal microparticles intermixed with the quantity ofsilicon microparticles in a selected ratio, the silicon microparticlesand the metal microparticles being bound to each other; wherein themicroparticle mixture is formed in a silicon-hybrid anode material layerhaving a thickness of between about 2 micrometers and about 15micrometers.
 2. (canceled)
 3. The silicon-hybrid anode material of claim1, wherein the silicon microparticles and the metal microparticles arebound to each other by including at least one binder material in themicroparticle mixture and heating the microparticle mixture.
 4. Thesilicon-hybrid anode material of claim 1, wherein the microparticlemixture is annealed.
 5. The silicon-hybrid anode material of claim 1,wherein the silicon microparticles have a size range of between about 1micrometer and about 20 micrometers.
 6. The silicon-hybrid anodematerial of claim 1, wherein the metal microparticles have a size rangeof between about 1 micrometer and about 30 micrometers.
 7. Thesilicon-hybrid anode material of claim 1, wherein a size of the siliconmicroparticles is substantially equal to a size of the metalmicroparticles.
 8. The silicon-hybrid anode material of claim 1, whereinthe selected ratio of the microparticle mixture includes between about10 percent and about 40 percent, by weight, of silicon microparticlesand between about 90 percent and about 60 percent, by weight, of metalmicroparticles.
 9. (canceled)
 10. The silicon-hybrid anode material ofclaim 1, wherein at least one silicon-hybrid anode material layer isincluded in a battery.
 11. The silicon-hybrid anode material of claim 1,wherein at least one silicon-hybrid anode material layer is included ina lithium-ion battery.
 12. The silicon-hybrid anode material of claim 1,wherein at least one silicon-hybrid anode material layer is included ina lithium-ion battery, the lithium-ion battery further including: alithium containing electrolyte that includes a quantity of separatormaterial; an anode disposed on a first side of the lithium containingelectrolyte and that includes the at least one silicon-hybrid anodelayer; and a cathode disposed on a second side of the lithium containingelectrolyte opposite from the first side of the lithium containingelectrolyte.
 13. A method comprising: forming a quantity of siliconmicroparticles; forming a quantity of metal microparticles; mixing thequantity of silicon microparticles and the quantity of metalmicroparticles in a selected ratio to form a microparticle mixture; andforming the microparticle mixture into a silicon-hybrid anode materiallayer having a thickness of between about 2 micrometers and about 15micrometers.
 14. The method of claim 13, wherein mixing the quantity ofsilicon microparticles and the quantity of metal microparticles in theselected ratio includes mixing a quantity of at least one bindermaterial into the microparticle mixture.
 15. The method of claim 13,wherein mixing the quantity of silicon microparticles and the quantityof metal microparticles in the selected ratio includes: mixing aquantity of at least one binder material into the microparticle mixture;and heating the microparticle mixture until the quantity of at least onebinder material is substantially evaporated away.
 16. The method ofclaim 13, wherein mixing the quantity of silicon microparticles and thequantity of metal microparticles in the selected ratio includes heatingthe microparticle mixture.
 17. The method of claim 13, wherein mixingthe quantity of silicon microparticles and the quantity of metalmicroparticles in the selected ratio includes heating the microparticlemixture and annealing the microparticle mixture.
 18. The method of claim13, wherein the silicon microparticles have a size range of betweenabout 1 micrometer and about 20 micrometers.
 19. The method of claim 13,wherein the metal microparticles have a size range of between about 1micrometer and about 30 micrometers.
 20. The method of claim 13, whereina size of the silicon microparticles is substantially equal to a size ofthe metal microparticles.
 21. The method of claim 13, wherein theselected ratio of the microparticle mixture includes between about 10percent and about 40 percent, by weight, of silicon microparticles andbetween about 90 percent and about 60 percent, by weight, of metalmicroparticles.
 22. The method of claim 13, wherein: mixing the quantityof silicon microparticles and the quantity of metal microparticles inthe selected ratio includes mixing a quantity of at least one bindermaterial into the microparticle mixture; and the binder is between about5 percent and about 10 percent by weight of the microparticle mixture.23. The method of claim 13, further comprising including thesilicon-hybrid anode material layer in a battery.
 24. (canceled)
 25. Themethod of claim 13, further comprising including the silicon-hybridanode material layer in a lithium-ion battery, the lithium-ion batteryfurther including: a lithium containing electrolyte that includes aquantity of separator material; an anode disposed on a first side of thelithium containing electrolyte and that includes the silicon-hybridanode layer; and a cathode disposed on a second side of the lithiumcontaining electrolyte opposite from the first side of the lithiumcontaining electrolyte.
 26. The silicon-hybrid anode material of claim1, wherein the silicon microparticles are formed by applying anelectromagnetic wave to a silicon source material, hydrogen, and argon.27. The method of claim 1, wherein forming the quantity of siliconmicroparticles includes applying an electromagnetic wave to a siliconsource material, hydrogen, and argon.
 28. A lithium-ion batterycomprising: a lithium containing electrolyte that includes a quantity ofseparator material; an anode disposed on a first side of the lithiumcontaining electrolyte and that includes a silicon-hybrid anode layer,the silicon-hybrid anode layer including an annealed microparticlemixture that includes: a quantity of silicon microparticles having asize range between about 1 micrometer and about 20 micrometers; and aquantity of metal microparticles having a size range between about 1micrometer and 30 micrometers and intermixed with the quantity ofsilicon microparticles in a selected ratio, the silicon microparticlesand the metal microparticles being bound to each other; and a cathodedisposed on a second side of the lithium containing electrolyte oppositefrom the first side of the lithium containing electrolyte.